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//#include <fstream>
//#include <cstdlib>

#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <vector>
#include <set>
using namespace std;

//const int pow2[] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824};
int MOD = 1000000000 + 7;

int pow2(int n)
{
    if(n==0) return 1;
    if(n==1) return 2;

    long long r = pow2(n/2);
    if(n%2==0)
    {
        return (r*r) % MOD;
    }
    else
    {
        return (r*r*2) % MOD;
    }

}

int N;
vector<vector<int> > V;

int str2int(const string& s)
{
    stringstream ss(s);
    int x;
    ss >> x;
    return x;
}

void parse(const string& f)
{
    vector<int> c(N+1);

    stringstream ss(f);
    string term;
    while(ss >> term)
    {
        int pos=0;
        int len=term.size();

        bool last = false;

        int znak = 1;

        if(term[0]=='(')
        {
            ++pos;
            --len;
        }

        if(term[term.size()-1]==')')
        {
            last = true;
            --len;
        }

        if(term[pos]=='~')
        {
            znak = -1;
            ++pos;
            --len;;
        }

        // pomijamy x
        ++pos;
        --len;

        int num = str2int(term.substr(pos,len));
        c[num] = znak;
        if(last)
        {
            V.push_back(c);
            for(int i=0; i<(int)c.size(); ++i)
                c[i] = 0;
        }

    }
}

void print(set<int> s)
{
    for(auto it=s.begin(); it!=s.end(); ++it)
        cout << *it << " ";
    cout << endl;
}

int compute(int n, set<int> s)
{
    //cout << "compute +" << n << endl;
    set<int> s_plus = s;
    for(auto it=s.begin(); it!=s.end(); ++it)
    {
        int i = *it;
        if(V[i][n]==1)
        {
            //cout << "  klauzula " << i << " spelniona" << endl;
            s_plus.erase(i);
        }
    }

    int partial_plus;
    if(s_plus.size()>0 && n<N)
    {
        partial_plus = compute(n+1, s_plus);
    }
    else if(s_plus.size()>0 && n==N)
    {
        partial_plus = 0;
    }
    else if(s_plus.size()==0 && n<=N)
    {
        partial_plus = pow2(N-n);
    }
    else
    {
        cout << "NIEMOZLIWE" << endl; exit(1);
    }
    ///////////////////////////////////////////////////

    //cout << "compute -" << n << endl;
    set<int> s_minus = s;
    for(auto it=s.begin(); it!=s.end(); ++it)
    {
        int i = *it;
        if(V[i][n]==-1)
        {
            //cout << "  klauzula " << i << " spelniona" << endl;
            s_minus.erase(i);
        }
    }

    int partial_minus;
    if(s_minus.size()>0 && n<N)
    {
        partial_minus = compute(n+1, s_minus);
    }
    else if(s_minus.size()>0 && n==N)
    {
        partial_minus = 0;
    }
    else if(s_minus.size()==0 && n<=N)
    {
        partial_minus = pow2(N-n);
    }
    else
    {
        cout << "NIEMOZLIWE" << endl; exit(1);
    }

    return (partial_plus + partial_minus) % MOD;
}

int main()
{
    //ifstream in("cnf_owca00.in");
    cin >> N;
    //cout << N << endl;
    string f;
    getline(cin, f);
    getline(cin, f);
    parse(f);

    /*
    for(int i=0; i<(int)V.size(); ++i)
    {
        for(int j=1; j<=N; ++j)
            cout << setw(2) << V[i][j] << " ";
        cout << endl;
    }
    */

    set<int> s;
    for(int i=0; i<(int)V.size(); ++i)
        s.insert(i);

    //cout << "START" << endl;
    int res = compute(1, s);
    cout << res << endl;
}